Urinary liver-type fatty acid-binding protein as a prognostic marker in patients with acute heart failure

Urinary liver-type fatty acid-binding protein (L-FABP) is expressed in proximal tubular epithelial cells and excreted into the urine during tubular injury. We hypothesized that high urinary L-FABP is associated with poor prognosis in patients with acute heart failure (AHF).

We analysed 623 patients (74 ± 13 years old; 60.0% male patients) with AHF. Urinary L-FABP levels were measured at the time of admission and adjusted for the urinary creatinine concentration. The primary endpoint was all-cause mortality. The median value and interquartile range of urinary L-FABP levels were 6.66 and 3.37-21.1 μg/gCr, respectively. Urinary L-FABP levels were significantly correlated with both beta-2 microglobulin and cystatin C levels; the correlation with the former was higher than that with the latter. During the follow-up of 631 (interquartile range: 387-875) days, 142 deaths occurred. A high tertile of urinary L-FABP level was associated with high mortality; this association was retained after adjusting for other covariates (second tertile hazard ratio 1.40, P = 0.152 vs. first tertile; third tertile hazard ratio 1.94, P = 0.005 vs. first tertile).

Urinary L-FABP is more closely associated with tubular dysfunction than with glomerular dysfunction. Tubular dysfunction, which was evaluated based on urinary L-FABP levels, in patients with AHF is associated with all-cause mortality and is independent of pre-existing risk factors. L-FABP should be considered for use in the prognosis of AHF.